The present invention relates a use of the electrocapture-based separation technology combined with mass spectrometry (e.g. sequence of polypeptides by collision-induce dissociation mass spectrometry, for the identification and/or characterization molecules of interest). In addition, it relates physical interfaces between electrocapture-based separations and different types mass spectrometers for on-line analysis, as well as the coupling of electrocapture-based separations, liquid chromatography and different types of mass spectrometrometers. It also relates the combination of the electrocapture-base separation technology with other liquid separation methods, as e.g. liquid chromatography, in order to achieve multidimensional separations prior mass spectrometrical analysis. The invention also relates to a separation device comprising a capture device, a fluidic connector e.g. an electrospray source, an electrospray interface-source and a mass spectrometer.